Treatment methods for lacrimal duct obstruction resulting in epiphora include: (i) probing by a lacrimal duct bougie, (ii) placement of a lacrimal duct tube; (iii) dacryocystorhinostomy (DCR); (iv) lacrimal canaliculization; (v) nasolacrimal duct plastic surgery; (vi) lacrimal caruncle moving surgery, and the like.
The probing by the lacrimal duct bougie in (i) is intended to insert a narrow tube called bougie into a lacrimal duct to open an obstructed site and reconstruct a flow path for a lacrimal fluid. The lacrimal duct tube (ii) to be used after the probing is a lacrimal duct intubation instrument that is placed in the lacrimal duct to maintain the flow path and reconstruct the tissues. These methods are conducted as first treatments in many cases due to their ease of treatment and minimal invasiveness. Meanwhile, the treatments (iii) dacryocystorhinostomy (DCR), (iv) lacrimal canaliculization, (v) nasolacrimal duct plastic surgery, and (vi) lacrimal caruncle moving surgery are highly effective but relatively invasive because of the need for incisions in a patient's face or drilling holes in bones, and thus are conducted a last resort.
After the probing by the lacrimal duct bougie (i), the lacrimal duct tube for use in the treatment method (ii) is placed in the lacrimal duct for maintaining of the flow path and reconstruction of the tissues. The placement of the lacrimal duct tube (ii) is easy, less invasive, and highly effective as compared to the foregoing treatment methods (iii) to (vi). Among such instruments, there is widely used a lacrimal duct tube in which its central part is formed by a narrow and soft tube or rod and its both sides are formed by hard and thick tubes, as disclosed in Patent Document 1 (for example, refer to Patent Documents 1, 2, and 3).
The lacrimal duct tube includes a tube and a pair of bougies that is inserted into the tube from apertures at both sides of the tube, and the bougies are operated to guide the tube into a lacrimal duct and place the tube there. As shown in FIG. 2 of Patent Document 1, the lacrimal duct includes lacrimal puncta (21 and 22), lacrimal canaliculi (23 and 24), a lacrimal sac (26), a nasolacrimal duct (27), and others. The lacrimal duct tube is inserted into the lacrimal duct.
However, to insert the lacrimal duct tube, it is necessary to grope for intra-lacrimal duct operations. The bougies are blindly operated and thus may break through the tube or make a hole at a site other than in the normal lacrimal duct (creating a false passage), which results in poor therapeutic outcomes.
In addition, in the field of lacrimal duct obstruction treatment, surgeries based on sheath guided endoscopic probing have been newly conducted in recent years. This technique is excellent in that a sheath as an outer casing made of Teflon (registered trademark) or polyurethane covering a lacrimal endoscope precedes the lacrimal endoscope in the lacrimal duct to observe from behind that the tip of the sheath opens the obstructed site in the lacrimal duct, and the sheath can be used as a guide for insertion of the tube to achieve exact tube insertion. Specifically, as shown in FIG. 1(a), a sheath 30 attached to a lacrimal endoscope 29 is inserted into an obstructed site 32 in an inferior nasal meatus 28 of the lacrimal duct 31 from an upper lacrimal punctum 21 through an upper lacrimal canaliculus 23 and passed through the obstructed site 32, and then the lacrimal endoscope 29 is removed. Next, as shown in FIG. 1(b), a lacrimal duct tube 33 is connected to the sheath 30, and the sheath 30 is pulled from the side opposite to the connection side of the lacrimal duct tube 33 to let the lacrimal duct tube 33 pass through the lacrimal duct 31. Next, as shown in FIG. 1(c), the sheath 30 is removed to place the lacrimal duct tube 33 in the lacrimal duct 31.
Next, although not shown, another sheath 30 attached to the lacrimal endoscope 29 is inserted into the obstructed site 32 in the inferior nasal meatus 28 of the lacrimal duct 31 from the lower lacrimal punctum 22 not to be put in the lacrimal duct tube 33 through the lower lacrimal canaliculus 24 and passed through the obstructed site 32, and then the lacrimal endoscope 29 is removed. Then, an end of the lacrimal duct tube 33 not passing through the obstructed site 32 is connected to the sheath 30, and the sheath 30 is pulled from the side opposite to the connection side of the lacrimal duct tube 33 to let the other end of the lacrimal duct tube 33 pass through the lacrimal duct 31. Lastly, the sheath 30 is removed to place the lacrimal duct tube 33 in the lacrimal duct 31.
However, the foregoing method needs to include the step of connecting the sheath 30 inserted into the patient's lacrimal duct and the lacrimal duct tube 33. In addition, occurrence of the disconnection between the sheath 30 and the lacrimal duct tube 33 could result in an unsuccessful surgery. In actuality, a wide variety of sheaths different in inner diameter and material are used. To ensure reliable procedure and reduction in complexity, the lacrimal duct tube needs to be capable of smooth insertion into the holes of sheaths of various materials, firm connection and adherence to the sheath during surgeries, and smooth operation in the lacrimal duct.
Meanwhile, instead of using the sheath, a lacrimal endoscope may be inserted into the lacrimal duct tube. For example, there is known a lacrimal duct treatment tool including: a lacrimal duct placement main body that has an outer diameter allowing insertion into the lacrimal duct and is formed of a flexible material; and a sheath part that is provided at the lower end of the lacrimal duct placement main body and is composed of a flexible cylindrical body formed of a harder material than that for the lacrimal duct placement main body (refer to Patent Document 4).
However, in the case of using the lacrimal duct treatment tool in the sheath guided endoscopic probing, the lacrimal duct treatment tool is long and is likely to be difficult to operate in general. In addition, it is necessary to separate the main body and the sheath part of the lacrimal duct treatment tool after placement in the lacrimal duct.
As described above, various methods for lacrimal duct obstruction treatment are currently employed, but it cannot be said that lacrimal duct tubes usable for any lacrimal duct obstruction treatment have been sufficiently developed, and the current lacrimal duct tubes have room for improvement.